diff --git a/etc/firebase-admin.extensions.api.md b/etc/firebase-admin.extensions.api.md
index ed9090aaee..127754c9c9 100644
--- a/etc/firebase-admin.extensions.api.md
+++ b/etc/firebase-admin.extensions.api.md
@@ -14,11 +14,19 @@ export class Extensions {
     //
     // (undocumented)
     readonly app: App;
-    // Warning: (ae-forgotten-export) The symbol "Runtime" needs to be exported by the entry point index.d.ts
     runtime(): Runtime;
 }
 
 // @public
 export function getExtensions(app?: App): Extensions;
 
+// @public
+export class Runtime {
+    setFatalError(errorMessage: string): Promise<void>;
+    setProcessingState(state: SettableProcessingState, detailMessage: string): Promise<void>;
+}
+
+// @public
+export type SettableProcessingState = 'NONE' | 'PROCESSING_COMPLETE' | 'PROCESSING_WARNING' | 'PROCESSING_FAILED';
+
 ```
diff --git a/src/extensions/extensions.ts b/src/extensions/extensions.ts
index 6e98f3575c..c4f6485539 100644
--- a/src/extensions/extensions.ts
+++ b/src/extensions/extensions.ts
@@ -36,8 +36,10 @@ export class Extensions {
 
   /**
    * The runtime() method returns a new Runtime, which provides methods to modify an extension instance's runtime data.
+   *
+   * This method will throw an error if called outside an Extensions environment.
    * 
-   * @returns A new Runtime object.
+   * @returns A new {@link Runtime} object.
    */
   public runtime(): Runtime {
     return new Runtime(this.client);
@@ -47,7 +49,7 @@ export class Extensions {
 /**
  * Runtime provides methods to modify an extension instance's runtime data.
  */
-class Runtime {
+export class Runtime {
   private projectId: string;
   private extensionInstanceId: string;
   private readonly client: ExtensionsApiClient;
diff --git a/src/extensions/index.ts b/src/extensions/index.ts
index 6283e630dc..486ad645d0 100644
--- a/src/extensions/index.ts
+++ b/src/extensions/index.ts
@@ -25,8 +25,9 @@ import { App, getApp } from '../app';
 import { FirebaseApp } from '../app/firebase-app';
 import { Extensions } from './extensions';
 
-export { Extensions } from './extensions';
- 
+export { Extensions, Runtime } from './extensions';
+export { SettableProcessingState } from './extensions-api';
+
 /**
   * Gets the {@link Extensions} service for the default app
   * or a given app.